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The Amazing Variety of Gears

by Rebekah Fuller, IQS editor

Rebekah Fuller Author Pic

From plastic gears for the smallest wind-up toy to two ton cast iron gears, the capabilities of gear manufacturers amaze me. I mean, being able to machine and cut gears from only a half inch through up to twenty feet in diameter is a pretty incredible range. Plus, being able to provide this kind of gear production all under one roof, turning out completely in-house customized and even emergency jobs – some gear manufacturers can do it all! Let’s take a look at some examples:

Plastic Gears Collection

Custom Made Gears by Commercial Gear & Sprocket Co

Customize Made Gears

Gear Assembly by Robust Gear Manufacturing

In the simplest terms, gears are used to transfer, speed up or slow down, and even change the direction of mechanical motion and/or torque. Industrial gears are utilized in all kinds of heavy duty equipment for dredging, agriculture, mining, water and waste management, material handling, machine shops and utility plants, and in the processing of pulp and paper, food, textiles, steel and aluminum, rubber, chemicals, cement, ore and more applications. Gearing is an essential component of speed reducers, motors and transmissions, increasing or decreasing crucial rotational speed.

Many of us probably rely most on the automotive gears that engage motion and power for our cars’ motors, transmissions, steering wheels and tires. Conically shaped bevel gears allow gears to interlock at perpendicular angles for applications such as rear end wheel torque in cars. Bevel gears are used as rear end gears in vehicles and industrial machinery requiring perpendicularly transmitted torque. The automotive industry also utilizes gearing for “rack-and-pinion” steering, in which the rack is a toothed shaft that is moved by a small interlocking pinion gear.

Robust Gear Set

Rack-and-Pinion Gear Components by

We are all familiar with clocks and know that the inner workings of mechanical ones are controlled by gears. And how cool are grandfather clocks and the gears that make them work! Intricate gear assemblies are a thing of beauty and necessary for so many uses. Who would have thought that a struggling Australian iron foundry would stay afloat in this tough economy by offering something that was missing locally – giant two ton cast gears. These $20,000 gears are used in belt-winder machines, which wind up conveyor belts for transportation.

It could take pages to describe all the various kinds of gears, but I will give a brief overview:

Spur gears (external and internal) are the simplest type of gear, having straight teeth radiating in alignment with the axis. They are often used as sprockets, thin gears with teeth that lock easily into roller chains, like in bicycle gears.

Different Spur Gears Disk Crank Sample of Spur Gears

Spurs by Omni Gear

Helical gears have teeth cut at an angle to axis of rotation in a spiral path. They can be aligned parallel or crossed, allowing gears to transmit torque perpendicularly.

Helical Gears

Helicals by Omni Gear

A worm drive is a combination of a worm (a gear formed like a screw) and a worm gear or wheel, which looks like a spur gear. The worm drives the gear, providing a high level of speed reduction for applications such as textile looms, packaging machinery, material handling and conveyor systems.

Worm Gear

Worms and Worm gears by Omni Gear

Other gearing shafts besides worms include straight side splines and serrated shafts and bushings.


Straight side splines by Omni Gear

Straight Side Splines

Shafts & Bushings by Robust Gear Manufacturing Inc

Precision machined custom gears and assemblies come in all sizes and types, including clusters, timing belt pulleys, metric gears, and special forms, and are used to create larger gear units, such as gearboxes, gear motors and gear reducers.